I have been programming SCADA/HMI/PLC's for many a year, but this is my first Unistream one. As i understand it there is a set of UDFB for functions which are useful, as some functions are thin on the ground within the Unilogic IDE. Typically the function Num to String is not supported, but it is in the UDFB download as I understand it. an any advise where I can download these UDFB's would be appreciated Many Thanks

Brett, Writing 1151 (start)  and 1150 (stop) does start and stop the drive, i also wrote the speed to the drive modbus adress 1. In order to let the drive turn the other way you have to use negative numbers. You can do this with writing multple vectors but i chose to create more nets and reading and writing  1 vector at a time. I also made a net to read the actual speed at adress 4. When you whant to read and write more data from and  to the ABB drive you can download the ABB documentation from their website with the modbus adressing table. Gert P.

That's actually a program crash within the PID server.  It's been a long time since that module has been updated.  What happens if you Auto Tune the loop without it? Joe T.

The first thing to do is load the PLC, connect it to the drive, and determine if the logic works to start and stop the drive.  Have you had a chance to do this yet?  It's kind of the reverse of V'ger touching the Creator, if you're a Star Trek fan.  You can't beat actually putting the hardware together.  If it's a 480V drive you can wire a control power transformer backwards to light it up on your work table.  Just be careful that you don't electrocute yourself. Once you've had a successful communication, you can move on to reading and writing other registers.  Usually you only write one and read many.  Modbus allows up to 125 contiguous registers in a Read operation. As Flex pointed out, Official Modbus starts counting at 1 and Unitronics Modbus starts at 0.  4xxxx means it's a holding register, so ignore the 4 when determining the address.  In other words, Modbus 40001 equals Unitronics address 0 as Gert did in net 4. Have a go at it and post your program with questions. Joe T.  

You can't compare an MF to an MI.  I don't know why it let you enter that.  You'll have to convert the MI to an MF register. Joe T.